Some cord reels are designed for use with headphone or mouse cables, AC adapter cords, or any such device that uses such cords. For example, Japanese Patent (Published) No. Heisei 11-246126 and Japanese Patent (Published) No. 2001-292218 describe a take-up system wherein the cord is inserted into the groove of a shaft attached to the center of a round casing or cover and then the shaft is wound to take up the cord. These systems can be downsized but the cord detaches from the cord reel or slips off the reel at the attachment point when the cord is extended.
A device that uses a take-up system that anchors and winds the cord around a round base plate between the top and bottom halves of a split casing is already in commercial use. In such a system the two cross-section areas are smaller because the take-up housing is divided and if the mechanism is downsized cord winding becomes less efficient due to the increase in the resistance to winding, making the mechanism more difficult to operate. With stereo headphones the cord is much thicker where the cords of the left and right headphones converge with the main trunk of the cord. With some stereo headphones the cords of the left and right headphones are not the same length. If the aforementioned system is downsized, the aperture that admits the cord becomes very small, so the junction where the cords of the left and right headphones converge will jam the aperture and winding will stop. Even if the cord aperture is enlarged, if the left and right cords are of different lengths the device will take up the cords only as far as the end of the short cord and the end of the long cord will remain hanging free.
A miniature light-weight cord reel equipped with a latch mechanism that allows attaching the center of any type of cord for a headphone or earpieces for mobile telephones and portable sound devices regardless of cord thickness or weight, affords greater operability and better take-up efficiency, allows winding past the point where left and right cords converge, and allows winding of left and right cords of different lengths has not yet been invented.